t() :: %ExFtx.Fill{
  base_currency: String.t() | nil,
  fee: number(),
  fee_currency: String.t(),
  fee_rate: number(),
  future: String.t(),
  id: pos_integer(),
  liquidity: String.t(),
  market: String.t(),
  order_id: pos_integer(),
  price: number(),
  quote_currency: String.t() | nil,
  side: String.t(),
  size: number(),
  time: String.t(),
  trade_id: pos_integer(),
  type: String.t()
}